New London - In a space on Tempel Green about two-thirds the size of a football field, Connecticut College is creating a subterranean showpiece for its environmental sustainability programs.

The college's charter states that no buildings could be constructed on the sweeping expanse at the center of the campus so that the views it affords to the mouth of the Thames River and Long Island Sound remain unobstructed, said Amy Martin, college spokeswoman. But the charter didn't put any restrictions on what could be built below ground.

This fall, the north end of the green was transformed - but only temporarily - into a 40,000-square-foot pit cordoned off by chain-link fences and warning signs. Inside, a beehive of hard-hatted KBE Building Corp. workmen, bulldozers, backhoes and well-drilling equipment has directed its efforts toward tapping into the power of the magma. This hot core at the Earth's center keeps subsurface temperatures a constant 55 degrees, regardless of whether it's 12 below or 100 degrees in the shade above.

The geothermal system under construction, which takes advantage of the difference between the surface and the underground temperatures, will provide all the heat and air conditioning for the college's new science center, also a work in progress. The building will consist of 25,000 square feet of renovated space, plus 10,000 square feet of new space.

The college, Martin said, committed to a green building policy in 2005 and has since undertaken several projects to improve energy efficiency and lower the use of greenhouse gas-emitting fossil fuels. The geothermal system, coupled with the design of the new science building, will be the largest to date.

"This is going to be a centerpiece of our sustainability efforts," said Josh Stoffel, the college's sustainability coordinator. "This is very symbolic of many of the different aspects that Connecticut College has adopted."

The project is scheduled for completion this spring, and the science building is slated to open by next fall. Once completed, the green will be restored to pastoral condition, with no visible sign of what's below.

"Tempel Green is a very, very important part of the campus," Martin said. "Sometimes it's an athletic field, sometimes students study here. Commencement is here."

On some future May afternoon, Stoffel said, "kids will be out here sunbathing on top of a system that's heating and cooling the new science building."

The system, explained Mike Guidera, construction manager for KBE Building, will consist of 44 wells 500 feet deep connected by two loops of six pipes each. A glycol-and-water mixture will travel through the pipes, which would be heated or cooled according to the season, and the temperature difference transferred through a system of compressors and pumps that would be located in the basement of the new science center.

The cost of the system is around $1 million - about $400,000 more than a conventional oil- or gas-burning HVAC system - but will be made up in reduced energy costs over six to seven years, Stoffel said.

Greenhouse gas emissions would also be about two-thirds less than with a conventional system, Martin said. The only emissions would come from the electricity required to run the heat pumps.

Page Owen, chairman of the college's Botany Department and faculty representative for the construction project, said the new science building and geothermal system will vastly improve the science facilities, replacing antiquated labs and classrooms in the 100-year-old New London Hall, which lacked air conditioning or proper temperature controls for experiments.

The new facilities will also enhance one of the college's most important academic programs in ways not possible before, Owen said.

"We have one of the country's oldest environmental studies programs, and to actually have this in place and to be able to show the students how it works will have much more power," he said.

Growth industry

The geothermal system at the college is one of several existing, under construction or planned in the region, including one at the new high school in Waterford and at an apartment complex for the disabled in New London.

Jack DiEnna Jr., executive director of the Geothermal National and International Initiative Inc., said the technology has been around for about 60 years. There are now about 1.5 million homes, institutions and commercial buildings nationwide that use geothermal systems.

Due to recent technology improvements, plus interest in green energy and ways to reduce energy costs, the geothermal industry has been growing at about 25 percent per year, DiEnna said. But it still represents only about 1 to 2 percent of all heating and cooling projects annually.

"If you have solar, you need to have the sun shining," DiEnna said. "If you have wind, you need to have the wind blowing. This technology can be done anywhere in the world. We've got them in Alaska, and we've got them in Guam. It's using the energy you already own under your feet."

In Connecticut, about 600 to 700 geothermal systems are in homes, commercial and institutional buildings, about 250 of which have been built in the last two years, said David Ljungquist, director of energy efficiency deployment for the Connecticut Clean Energy Finance and Investment Authority. The quasi-public agency has been overseeing a $5 million rebate program for geothermal projects that came from the federal government as part of the American Recovery and Reinvestment Act, he said.

According to the Union of Concerned Scientists, geothermal energy "has the potential to play a significant role in moving the United State toward a cleaner, more sustainable energy system." Its website statement also notes that homeowners can receive a 30 percent investment tax credit, available through 2016, for installations of Energy Star-certified geothermal heat pumps.

There has also been about $450 million in federal investment since 2009 in research and development of geothermal energy projects.

Noting recent U.S. Geological Survey studies of the potential capacity for geothermal energy production, the statement said: "This resource could one day supply nearly all of today's U.S. electricity needs."